This method of ring formation, like that described by Montgomery ('03) for the Amphibia, is of very frequent occurrence in the spermatocytes of the Coleoptera.
Whole cysts of giant first spermatocytes were found both in growth stages (fig.
All of the equatorial plates of the first spermatocytes showed 8 chromosomes, as usual.
There is no synizesis and no polarized or bouquet stage, but the nuclei of all of the spermatocytes contain a continuous spireme throughout the growth stage.
The equatorial plates of the two resulting kinds of second spermatocytes appear in figures 75 and 76.
In the first maturation mitosis it is attached to one pole of the spindle, does not divide, but goes to one of the two second spermatocytes (figs.
In addition to this, in one-half of the spermatid nuclei there is a condensed mass of chromatin which is evidently the derivative of the odd chromosome of the spermatogonia and spermatocytes (figs.
Most of the spermatocytes contained 10 chromosomes, one of which was plainly an unequal pair.
A pair of second spermatocytes in metaphase, two chromosomes connected, x the odd chromosome.
Then when the heterotypic division takes place and the number of chromosomes is halved, we shall have two spermatocytes with N-1 chromosomes from one of the first spermatocytes and one with N and one with N-1 from the other.
In some forms the reduction division occurs in the secondary spermatocytes instead of the primary.
Secondary spermatocytes are still evident near the periphery of the tubules but they are much less numerous than spermatids.
The testes of specimens that were nearly mature contained primary and secondary spermatocytes but lacked lumina; it was thought that such individuals would have matured in the following summer and bred in the following autumn.
Spermatogenesis is well under way by mid-June; at this time, two or three distinct layers of primary and secondary spermatocytes are present and these cells outnumber the Sertoli cells.
Spermatids appear in late June and a few of them undergo metamorphosis in early July; by mid-July, spermatids and secondary spermatocytes are the dominant cells in the seminiferous tubules, although spermatogonia are still active.
Primary spermatocytes appear in the tubules from mid-May to early June.
The germinal epithelium is still semiactive and small groups of primary spermatocytes are present in nearly all of the tubules.
The spermatogonia are the cells of the testis; these produce by division the spermatocytes (progametes), which divide and give rise to the spermatids.
In most cases which have been investigated the divisions by which the spermatids arise from the spermatocytes are two in number, so that each spermatocyte gives origin to four spermatids.
Curiously enough there appears in the nucleus of every spermatid a body similar to the element x of the spermatocytes of the first order (figs.
The spermatocytes of the second order go into a complete resting stage before they are completely separated, and one of a pair shows the element x, while it is lacking in the other (fig.
Spermatocytes of first order; conjugation of the chromosomes.
It passes into one of each pair of spermatocytes of the second order, persists during the rest stage, appears in the second mitosis as a dyad and then divides, going into one-half of the spermatids.
Two resting spermatocytes of the second order, one containing element x, the other not.
McClung is inclined to believe that the accessory chromosome is an element common to all of the male reproductive cells of Arthropods, and probably to vertebrate spermatocytes as well ('02).
Condensation of chromatin--spermatocytes of first order immediately before mitosis.
It gradually increases in size, is a conspicuous element in the first maturation spindle, goes into one of each pair of spermatocytes of the second order, and there degenerates during the rest stage between the two maturation mitoses.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "spermatocytes" in a variety of sentences. We hope that you will now be able to make sentences using this word.
